The present invention relates generally to routing call processing communications in a telecommunications system.
Telecommunications terminals connect subscriber lines, such as POTS (Plain Old Telephone Service) lines, ISDN (Integrated Services Digital Network) lines, E1 (E1ectronic Interface Level 1) lines, and optics lines, to telecommunications exchanges and other telecommunications equipment. An access terminal contains channel unit card slots that accept channel unit cards. The channel unit cards, or line cards, convert analog or digital signals from subscriber lines into formatted digital data signals. Different types of channel unit cards service different types of subscriber lines.
An access terminal constructs a single time division multiplexed (TDM) signal from several channel unit cards' formatted digital data signals for transmission to remote telecommunications equipment. The terminal also demultiplexes TDM signals received from remote telecommunications equipment to deliver formatted digital data back to the channel unit cards. Channel unit cards convert the formatted digital data into a form suitable for transmission over subscriber lines.
Two telecommunications terminals can be connected "back to back" to form a digital carrier loop network. A digital carrier loop network typically includes a remote terminal placed near a business or residence and a central terminal placed in a central exchange connected to a telecommunications switch. The remote terminal and central terminal communicate over a single line carrying TDM signals. This configuration connects subscribers to the telecommunications switch.
Typically, the telecommunications switch and local exchange carrier network operate according to a protocol that is country-specific or vendor-specific. Such country-specific or vendor-specific protocols impose various signaling and other requirements that can affect multiple system components.